Polypropylene Filled Nano-CaCO3 Composites: Effect of Nano-CaCo3 Loadings and Reprocessing on the Crystallization Behavior of the Nanocomposites

Abstract

This paper discusses about the production and characterization (i.e. morpohology and crystallization behavior) of polypropylene filled nano-CaCO₃ composites (i.e. PNCCs). The PNCCs were successfully prepared via melt mixing/compounding process using nano-CaCO₃ masterbatch in a twin-screw extruder (TSE) machine. Different nano-CaCO₃ concentrations (i.e. 5, 10 and 15 wt%) and two times process (i.e. 1^st cycle and 2^nd cycle) were used to analyze the influence of nano-CaCO₃ concentrations and reprocessing on the morphology and crystallization properties of the PNCCs. The morphology and crystallization properties of the PNCCs were studied using SEM and DSC, respectively. The SEM images exhibited that at low nano-CaCO₃ concentration (i.e. 5 wt%), the nano-CaCO₃ fillers were well distributed and dispersed in the PP matrix for both NCC-5-I and NCC-5-II samples. Nevertheless, the size of the nanofillers in NCC-5-II sample were smaller than that of the NCC-5-I sample. Additionally, the DSC crystallization thermograms showed that crystallization temperature (T_c) and onset crystallization temperature (T_oc) of the PNCCs were higher than the pristine PP. The increases of T_c and T_oc for both PNCCs (i.e. 1^st cycle and and 2^nd cycle) were not much different, which were about 4-5 °C and 3-4 °C, respectively.